Levendusky – Anatomy and Physiology II – Fetal Pig Dissection (Unit: Reproductive System)
Fetal Pig Dissection
Group Members:
Group Member Roles:
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Team Member Roles:
Reader – reads lab directions, makes sure group is correctly following the procedure
Recorder – writes down all answers/records group input on the lab sheets
*Answers are provided as a group effort*
Team Leader – gathers any materials needed, makes sure group is on task/watches time, asks any questions that may
arise
Dissector – dissects the fetal pig following directions from the reader and team leader
Background:
Mammals are vertebrates having hair on their body and mammary glands to nourish their young. The majority
are placental mammals in which the developing young, or fetus, grows inside the female's uterus while attached to a
membrane called the placenta. The placenta is the source of food and oxygen for the fetus, and it also serves to get rid
of fetal wastes. The dissection of the fetal pig in the laboratory is important because pigs and humans have the same
level of metabolism and have similar organs and systems. Also, fetal pigs are a byproduct of the pork food industry so
they aren't raised for dissection purposes, and they are relatively inexpensive.
Objectives:
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Identify important external structures of the fetal pig.
Identify major structures associated with a fetal pig's urogenital system.
Compare the functions of certain organs in a fetal mammal with those of an adult mammal.
Materials:
preserved fetal pig, dissecting pan, dissecting kit, dissecting pins, string, plastic bag, metric ruler, paper towels
Pre-lab:
Before observing internal or external structures of the fetal pig, use your dissection manual, textbook, and dissection
notebook to answer the pre-lab questions on the fetal pig. You may have to refer to more than one dissection manual to
answer all the questions so trade and share with other dissection groups.
Safety:
*Review your safety contract before beginning the dissection.
*Any violation of the safety contract will result in ejection from the lab and a zero for your evidence
grade(s).
*Wear your lab apron and safety goggles at all times.
*Watch your time and be sure to clean up all equipment and working area each day before leaving.
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Levendusky – Anatomy and Physiology II – Fetal Pig Dissection (Unit: Reproductive System)
Fetal Pig Dissection Student Directions
Part I - External Anatomy
1. Obtain a fetal pig and rinse off the excess preservative by holding it under running water. Lay the pig
on its side in the dissecting pan and locate dorsal, ventral,& lateral surfaces. Also locate the anterior
and posterior ends.
2. A fetal pig has not been born yet, but its approximate age since conception can be estimated by
measuring its length. Measure your pig's length from the tip of its snout to the base of its tail and
record this on your hand-in. Use the length/age chart on this sheet or the inside cover of your
dissection manual to determine the age of your fetal pig & record this.
3. Examine the pig's head. Locate the eyelids and the external ears or pinnae. Find the external nostrils.
4. Study the pig's appendages and examine the pig's toes. Count and record the number of toes and the
type of hoof the pig has.
5. Locate the umbilical cord. With scissors, cut across the cord about 1 cm from the body. Examine the 3
openings in the umbilical cord. The largest is the umbilical vein, which carries blood from the placenta
to the fetus. The two smaller openings are the umbilical arteries which carry blood from the fetus to
the placenta.
6. Lift the pig's tail to find the anus. Study the ventral surface of the pig and note the tiny bumps called
mammary papillary. These are present in both sexes. In the female these structures connect to the
mammary glands.
7. Determine the sex of your pig by locating the urogenital opening through which liquid wastes and
reproductive cells pass. In the male, the opening is on the ventral surface of the pig just posterior to
the umbilical cord. In the female, the opening is ventral to the anus. Record the sex of your pig.
8. Carefully lay the pig on one side in your dissecting pan and cut away the skin from the side of the face
and upper neck to expose the masseter muscle that works the jaw, lymph nodes, and salivary glands.
Label these on your hand-in.
9. With scissors, make a 3-cm incision in each corner of the pig's mouth. Your incision should extend
posteriorly through the jaw.
10. Spread the jaws open and examine the tongue.
11. Observe the palate on the roof of the mouth. The anterior part of the palate is the hard palate, while
the posterior part is the soft palate.
12. Locate the epiglottis, a cone-shaped structure at the back of the mouth. Above the epiglottis, find the
round opening of the nasopharynx. This cavity carries air from the nostrils to the trachea, a large tube
in the thoracic which supplies air to the lungs.
13. Dorsal to the glottis, find the opening to the esophagus. Examine the tongue and note tiny projections
called sensory papillae.
14. Examine the teeth of the pig. Canine teeth are longer for tearing food, while incisor are shorter and
used for biting. Pigs are omnivores, eating plants and animals.
15. Label the drawing of the inside of the pig's mouth.
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Levendusky – Anatomy and Physiology II – Fetal Pig Dissection (Unit: Reproductive System)
Part II - The Incision
1. Be sure to wear your lab apron and eye cover. Obtain your dissecting equipment and pig from the
supply cart.
2. Place the fetal pig ventral side up in the dissecting tray.
3. Tie a string securely around a front limb. Run the
string under the tray, pull it tight, and tie it to the
other front limb. Repeat this procedure with the hind
limbs to hold the legs apart so you can examine
internal structures.
4. Study the diagram at the right. The dashed lines
numbered 1-5 show the first set of incisions that you
will make. To find the exact location for the incision
marked 2, press along the thorax with your fingers to
find the lower edge of the ribs. This is where you will
make incision 2.
5. With scissors, make the incisions in order, beginning
with 1. Be sure to keep the tips of your scissors
pointed upward because a deep cut will destroy the
organs below. Also, remember to cut away from
yourself.
6. After you have made your incisions through the body
wall, you will see the peritoneum, a thin layer of
tissue that lines the body cavity. Cut through
the peritoneum along the incision lines.
7. Spread the flaps of the body wall apart. Cut the umbilical vein which extends through the liver.
8. Once the vein is cut, carefully pull the flap of skin, including the end of the umbilical cord between the
hind legs. You are now able to see the organs of the abdominal cavity.
Urogenital System
1. Be sure to wear your lab apron and eye cover.
2. Remove the digestive organs to study the excretory (urinary) and reproductive organs that make up
the urogenital system.
3. Locate the large, bean-shaped kidneys lying against the dorsal body wall. Notice that they are covered
by the peritoneum. Kidneys filter wastes from blood.
4. Find the ureters, tubes which extend from the kidneys to the bag-like urinary bladder. The urinary
bladder lies between the umbilical arteries and temporarily stores liquid wastes filtered from the
blood.
5. Lift the urinary bladder to find the urethra, the tube which carries urine out of the body. Follow the
urethra to the urogenital opening on the outside of the pig's body.
6. Make sure that incision #6 extends all the way to the anus but be careful to not cut too deep and
damage the internal organs.
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Levendusky – Anatomy and Physiology II – Fetal Pig Dissection (Unit: Reproductive System)
7. Follow the directions below for locating the excretory and reproductive organs in either a male or
female pig. When you finish observing the organs in a pig of one sex, exchange specimens with another
classmate to view the organs in a pig of the opposite sex.
Male System
8. In the male pig, locate the two scrotal sacs at the posterior end of the pig. If the pig is in the later
stages of development, you will find a testis in each sac. If the pig is in an early stage of development,
the oval-shaped testes will be in the abdominal cavity. These testes have not yet descended into the
scrotal sacs.
9. On each testis, find the coiled epididymis. Sperm cells produced in the testis pass through the
epididymis and into a tube called the vas deferens. This tube crosses over a ureter and enters the
urethra.
10. Follow the urethra to the penis, a muscular tube lying just below the skin posterior to the umbilical
cord. In mammals, the penis is the organ that transfers sperm.
11. Label the diagram of the male urogenital system on the handout.
Female System
12. In the female pig, find the two bean-shaped ovaries at the posterior end of the abdominal cavity.
Observe the coiled Fallopian tube attached to each ovary, which carries eggs from the ovary.
13. Follow the Fallopian tube to the uterus. The uterus is dorsal to the urinary bladder and the urethra.
14. Trace the uterus to a muscular tube called the vagina. The vagina will appear as a continuation of the
uterus. Sperm from the male are deposited into this organ during mating. The vagina and the urethra
open into a common area called the urogenital sinus. This cavity opens to the outside at the urogenital
opening.
15. Label the diagram of the female urogenital system on the handout.
*Important: Make sure that you view both the male and female fetal pig reproductive system. You do not
know if your practical will be on a male or female fetal pig.*
When you have completed your study of the urogenital system of both sexes, clean up your materials and
work area.
[Make sure to wash and dry all dissection tools, case and dissection tray. Spray down and wipe your table.]
Dispose of the dissected specimen in the appropriate garbage. Thoroughly wash your hands with soap.
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